In the formation of mine galleries and in the stabilization of subterranean structures generally, it is known to provide drilling and bolting means which have the capacity of drilling a bore, sometimes referred to as a borehole, in the rock structure to receive the bolt, and to insert the bolt with or without a material which suffices to permit anchoring of the bolt in place. The bolt may be provided with a screwthread or other helical rib formation, may be simply inserted axially or rotated and may be accompanied by a bag, pouch or other container of an epoxy resin, for example, which can be hardened in place.
Such drilling and bolting means can comprise a vehicle body which can move through the mine gallery on wheels or treads, an arm articulated on this body so as to be able to manoeuver the drilling and bolting head into practically any position opposite a wall or roof of the gallery, a drilling and bolting turret on this head which can alternately position a drill and a bolt-setting mechanism at the location at which the bolt is to be set and, of course, a mechanism for operating the arm from a remote location, a mechanism for rotating the rocket drill and guiding it to form the borehole, and a mechanism for setting the bolt in place.
It is also known with such means to provide a bolt magazine in which a plurality of bolts may be accummulated for individual feeding to the bolting turn, and a transfer device for shifting the bolts to the bolting head.
The turret can be of the type comprising a girder mounted to pivot about an axis at the end of a support arm and comprising means for guiding two carriages as they slide, in a direction parallel to the pivoting axis of the girder, one carriage for drilling a hole and the other for the introduction of a bolt into the hole drilled and for tightening it, as well as means for controlling the advance and return movements of the two carriages, other control means being provided for the pivoting of the girder in order to bring the second carriage in line with the axis of the hole drilled previously by the first carriage and also for the longitudinal movement of the girder arrangement parallel to its pivot axis.
A turret of this type, which is used in the field of mining, in particular for operations of supporting the roof and the faces of a mine-level or gallery, is already described for example by British Pat. No. 1 016 125. This turret is equipped for drilling a hole by means of the first carriage which drives a drilling bit and then in order to introduce an anchoring bolt into the hole and to tighten it by means of the second carriage constituting a screwing arrangement. Anchoring of the apparatus to the roof or face of the level is carried out along the pivot axis of the turret, in order that before its introduction operation, the axis of the bolt corresponds exactly to the axis of the hole drilled. A turret of this type is advantageously associated with a bolt magazine, in order to be able to drill a series of holes and introduce bolts into the latter progressively, virtually without manual intervention.
In present constructions of turrets of this type, if the bolt is taken from a magazine, it is received and in all cases held in position during introduction by two grippers or "small forks" whose supports are fixed to the turret.
These grippers must be retractable in order to allow the passage of the second carriage constituting the screen arrangement, which necessitates movable parts, pivot axis, return springs, stops, which complicate the construction.